Automatic register controller for flexo printing press

[Tam1117]

  We are building a ARC (Automatic register controller ) system for a flexo press. The press is 130' long with 20 stations, max speed is 100'/min.
  We have some questions and need your expert advices, thanks in advance for the helps.
     .There will be 20 stepper motors (or servo if we have enough budget)to control, what is the best PLC(s) for the project Do-more or BRX?
     .Can 1 plc can control 20 stepper motors (Automationdirect stepper drive)( we want to use 1 encoder )? 
     .What is the best way to control: high speed outputs or SCL commands?   
  That all we have for now but I will ask more question later.

  Thank you all.
     

[plcnut]

1 encoder for ALL the steppers? or 1 encoder for EACH of the steppers?
High speed IO would be MUCH better than SCL in an application like this.

[BobO]

  We are building a ARC (Automatic register controller ) system for a flexo press. The press is 130' long with 20 stations, max speed is 100'/min.
  We have some questions and need your expert advices, thanks in advance for the helps.
     .There will be 20 stepper motors (or servo if we have enough budget)to control, what is the best PLC(s) for the project Do-more or BRX?
     .Can 1 plc can control 20 stepper motors (Automationdirect stepper drive)( we want to use 1 encoder )? 
     .What is the best way to control: high speed outputs or SCL commands?   
  That all we have for now but I will ask more question later.

  Thank you all.
     

Minor thing first...Do-more is the control technology (engine and programming software); the DM1x is the PLC that runs Do-more; BRX, DL205, and Terminator are all platforms that have DM1x CPUs available. So I think your question is actually Do-more on BRX vs Do-more on DL205.

Until BRX releases the HSIO expansion, fast I/O is is limited to the onboard I/O, which means you would need to use multiple BX-DM1E-X CPUs. Since the motors are distributed over 130 feet, you really don't want to run motor wiring that far anyway, so that doesn't seem like a big limitation. You could also do it from a single H2-DM1E (DL205 platform) with multiple CTRIO2 modules, and use the Ethernet I/O Master to distribute CTRIO2s across multiple bases down the line. I'm not sure that there is a big advantage to either approach, although I'm guessing that the BRX system would cost less.

We did a fun application with BRX doing almost exactly the same thing. We used 7 BX-DM1E-18s for the axis controls, and an 8th BRX CPU for the upstream comms and master control. All 20 axes had a stepper and an encoder, and we closed the loop on the target position with a "simple square root of error" type control loop. The mechanical were a little sloppy (low budget/little time) but it worked great. We did it mostly just to show off BRX and help a local church with an annual conference. Youtube link is a short video demonstrating one of the animations.

https://youtu.be/5sfSlrvg9C8

[Tam1117]

Thank you for the answers.
"1 encoder for ALL the steppers? or 1 encoder for EACH of the steppers?
High speed IO would be MUCH better than SCL in an application like this."
 One encoder for all the steppers.
"Until BRX releases the HSIO expansion, fast I/O is limited to the onboard I/O, which means you would need to use multiple BX-DM1E-X CPUs"
That means we have to use 3 BRX CPUs (8 high speed outputs each PLC x 3 = 24).
  There will be 1 main HMI (C-more)for the system and 1 small HMI (C-more micro) for each station (20 total).
    The 1st PLC will be connected to main HMI (C-more) and 8 C-more micro (each will control 1 stepper).
    The 2nd will be the same as 1st.
    The 3rd PLC will be connected to main HMI (c-more) and the rest of C-more (4).
  Is that possible? What is the best way to network them?
Thanks again Plcnut & BobO you guys are awesome!

                                         

[BobO]

That means we have to use 3 BRX CPUs (8 high speed outputs each PLC x 3 = 24).

Even though there are 8 high speed outputs, there are only 3 axis controllers, so a single CPU can only control 3 steppers.

What pulse rate do you need?

[Tam1117]

    Hi BobO

   We need pulse rate around 6kz.
   So we will need 7 PLCs. Now I have to figure how to get the encoder signal to 7 PLCs!
   I watch your video. Can you post the programs?

[BobO]

   So we will need 7 PLCs. Now I have to figure how to get the encoder signal to 7 PLCs!

In the video, we generated the desired target position for each louver in the master PLC, and used PEERLINK to publish to to the slave controllers (about 10Hz rate). Each axis then used a simple loop equation to drive a velocity to the axis.

   I watch your video. Can you post the programs?

The slave program was very simple.

We generate AxisX's error from PL[AxisXPosition]:S (target position) and $AxisX.CurrentPosition (the axis' current position)

We generate the axis' velocity from the equation Velocity = Sqrt(Error) * Gain

The key to making it work well is to set the axis accel/decel parameters as high as the stepper will allow, and then increasing the Gain term to the highest value before the axis starts ringing. View the target and axis current position in a trend view, and it becomes pretty obvious when the loop starts to get unstable.

This approach is a simple follower. There are other ways that could be used to tighten the control if this doesn't work well, but this is easy and a good starting point.

[Tam1117]

  Thanks BobO,

Now we have 7PLCs, 1 main HMI (control all stations), 20 small HMIs (control each station),
can we put all of them on Ethernet ? (Each PLC will be connected with 3 C-more micro HMIs and main HMI)

[BobO]

  Thanks BobO,

Now we have 7PLCs, 1 main HMI (control all stations), 20 small HMIs (control each station),
can we put all of them on Ethernet ? (Each PLC will be connected with 3 C-more micro HMIs and main HMI)

Sure. Comms will be pretty busy, but it will be fine. I would definitely make sure that the poll rate of each HMI panel was as low as will give you a responsive system, but the bandwidth should be more than adequate to do what you need. Spreading the HMI's across the PLCs is definitely helpful. You can use PEERLINK to share relevant data between the PLCs. If you need more data than PEERLINK supports or if 10Hz is too slow, you can use RX/WX instructions in the PLCs. They can move data much faster than 10Hz, or much slower, which can also be helpful.

Do-more is *very* good at comms. There are many ways to solve what you are doing if the first thing doesn't work as well as you hope.

[Tam1117]

   Thanks guys.

[Goethe]

This one is using AXFOLLOW

https://youtu.be/pjaxVuTHc7o

[BobO]

This one is using AXFOLLOW

https://youtu.be/pjaxVuTHc7o

Que paso, amigo!?

Thanks for posting that!

[Goethe]

No problem!

BTW those are Sure Servos, so it can go up to 3KW.

Regards

[BobO]

BTW those are Sure Servos, so it can go up to 3KW.

The previous demos you did like that were steppers, weren't they? Or is that the same demo you did many months ago?

[Goethe]

Yeap, the first generation were steppers. But we all know the limitations for steppers.

We always want more and better, So I changed them for Sure Servos.

With 3KW per unit many good things may come to life  

Best regards